U.S. Pat. No. 4,839,118 discloses a glove compartment box with a plastic rear wall portion that has integral flanges thereon thermally formed to fasten the rear wall with respect to the outer shell of the glove box.
While suitable for its intended purpose, the '118 patent does not address the problem of how to form a return flange at the belt trim support of a vehicle door panel so as to avoid thermal stress conditions in the vehicle door panel which will cause it to be warped.
One approach for forming vehicle door panels with return bends on the belt trim support is to provide an injection molding machine with dies configured to have the return bend formed therein. The return flange portion of the finished part constitutes a die-locked feature which can only be formed by use of retractable die members that add to the cost of injection molding machines.